Background technology
In the past, as the mean value from the direct current of DC power supply is carried out Calculation Method, known have on the power line from the DC power supply to the DC-to-AC converter current sensor is set, thereby detect this direct current, and carry out the method for integration by resistance and electric capacity.For example, be disclosed in the flat 7-67248 communique of Japanese Patent Application Laid-Open (the 5th page, the 1st figure, the 2nd figure).
Figure 23 represents this DC-to-AC converter in the past and the circuit around it.The control circuit 108 of DC-to-AC converter 121 is based on rotary speed instruction signal (not shown) etc., the switch element 2 that constitutes inverter circuit 37 is controlled, by will changing (switching) with the PWM modulation, thereby alternating current is outputed to stator coil 28 as the inscape of motor 30 from the direct voltage of battery 1.Then, be output power from rotor 29.For switch element 2, upper arm switching element is defined as U, V, W, the underarm switch element is defined as X, Y, Z.As switch element 2, use transistor, IGBT etc.The diode 3 that constitutes inverter circuit 37 becomes the backflow route of the electric current that flows through stator coil 28.
Between battery 1 and inverter circuit 37, comprise current sensor 6.The instantaneous value of the direct current that is detected by this current sensor 6 is sent to control circuit 108 via operational amplifier 11 by former state.Then, be used to the protection etc. of switch element 2.On the other hand, in the integrating circuit of forming by resistance 12 and electric capacity 13, be transformed to mean value via the instantaneous value of the direct current of operational amplifier 11, and be sent to control circuit 108.Then, obtain long-pending with the voltage of battery 1, thereby calculate input power DC-to-AC converter 121.This input power of DC-to-AC converter 121 is become the consumed power of battery 1.Limit indispensable to the calculating of the input power of DC-to-AC converter 121 in the motor and the consumed power that to power termination are consumed power as the battery 1 of DC power supply.
On the other hand, known have for the High Accuracy Control motor, and, be the method that phase current detects for sinuous alternating current is outputed to motor to motor current.For example, be disclosed in the Japanese Patent Application Laid-Open 2000-333465 communique (the 8th page, the 1st figure).Below, this mode is described.
Figure 24 represents this DC-to-AC converter in the past and the circuit around it.Between inverter circuit 37 and motor 31, comprise the current sensor 8 and the current sensor 9 that are used to detect phase current.
The control circuit 104 of DC-to-AC converter 120 is from the phase current values of current sensor 8 input U phases, from the phase current values of current sensor 9 input W phases.In addition, by using the current law of kirchhoff, thereby calculate the phase current values of remaining V phase according to these two current values at the neutral point of stator coil 28.Based on these current values, computing constitutes the induced voltage of 32 pairs of stator coils 28 of Magnmet rotor of motor 31, thereby the position of Magnmet rotor 32 is detected.Then,, the switch element 2 that constitutes inverter circuit 37 is controlled, by will changing with the PWM modulation, thereby sinuous alternating current is outputed to stator coil 28 from the direct voltage of battery 1 based on rotary speed instruction signal (not shown) etc.
About the method for the phase current that detects motor, also known have an additive method.For example, be disclosed in the Japanese Patent Application Laid-Open 2003-209976 communique (the 21st page, the 14th figure).
Figure 25 represents DC-to-AC converter and the circuit around it.Between underarm switch element and battery 1, comprise the shunt resistance that is used to detect phase current.That is, between U phase underarm switch element X and ground wire, be provided with shunt resistance 15, between V phase underarm switch element Y and ground wire, be provided with shunt resistance 16, between W phase underarm switch element Z and ground wire, be provided with shunt resistance 17.
The control circuit 107 of DC-to-AC converter 122 comes the phase current of each phase of computing according to these voltages from each shunt resistance.The phase current values that calculates based on this quilt, rotary speed instruction signal (not shown) etc., 107 pairs of switch elements 2 that constitute inverter circuit 37 of control circuit are controlled, change by modulating with PWM, thereby sinuous alternating current will be outputed to stator coil 28 from the direct voltage of battery 1.
In addition, in Figure 23, used operational amplifier 11, but be not indispensable.In Figure 24, Figure 25, omitted operational amplifier.
Between above-mentioned DC power supply (battery) and inverter circuit, have in the DC-to-AC converter of current sensor, can the mean value from the direct current of DC power supply be calculated.For this reason, except current sensor and operational amplifier, also the integrating circuit that need form by resistance and electric capacity, be used for A/D port to the input of the microcomputer in control circuit average current.And the resistance value of the resistance in the integrating circuit, the capacitance of electric capacity exist discrete, variations in temperature, and the computational accuracy of mean value is reduced.And then, related between the integrated value that also needs to obtain resistance and electric capacity and the actual average current, therefore improving precision becomes problem.In addition, element increases, so miniaturization, raising reliability become problem.
Between inverter circuit and load (motor), have the DC-to-AC converter that is used for current sensor that load current (phase current of motor) is detected, can't measure direct current from DC power supply.Therefore, average current can not be obtained, the consumed power of DC power supply can't be calculated.Though can be according to the AC power of phase current computing to motor, need carry out computing to the phase difference of electric current and voltage, PWM voltage etc., the computational burden of microcomputer that constitutes control circuit is excessive.In addition, when the computing AC power replaces direct current power, because of the consumed power that does not comprise DC-to-AC converter incorrect.
Between underarm switch element and DC power supply (battery), comprise the DC-to-AC converter of the shunt resistance that is used for detecting phase current, can't measure direct current from DC power supply.Therefore, produce and above-mentioned same problem.
Embodiment
Below, use the description of drawings embodiments of the present invention.
(execution mode 1)
Fig. 1 represents the circuit diagram of the DC-to-AC converter of embodiments of the present invention 1.Be that with difference deleted the integrating circuit of being made up of resistance 12 and electric capacity 13 in DC-to-AC converter 21, this integrating circuit is used to obtain mean value between operational amplifier 11 and control circuit 5 as Figure 23 of the circuit diagram of in the past DC-to-AC converter.Thus, the integrated value of resistance 12 and electric capacity 13 is deleted to the input of control circuit 5.In addition, will with upper arm switching element U, V, W, each diode that underarm switch element X, Y, Z are connected in parallel is defined as 3U, 3V, 3W and 3X, 3Y, 3Z respectively.In addition, other use same numerals that exist together mutually.
Among Fig. 1, the control circuit 5 of DC-to-AC converter 21 is based on rotary speed instruction signal (not shown) etc., the switch element 2 that constitutes inverter circuit 37 is controlled, by will from DC power supply 1 (below, be designated as battery) direct voltage change with PWM modulation, thereby alternating current is outputed to stator coil 28 as the inscape of motor 30.The peak value of the direct current that is detected by current sensor 6 is sent to control circuit 5 via operational amplifier 11.Then, be used to the judgement etc. of protection switch element 2.In addition, control circuit 5 calculates the direct current mean value between battery 1 and the DC-to-AC converter 21 based on the peak value of above-mentioned conversion and direct current.
For the calculating of this mean value, below be that example describes with the sine wave drive DC-to-AC converter of the alternating current of sine wave output shape.Fig. 2 is the illustration of expression sine wave drive with each duty ratio characteristics of exporting mutually in the DC-to-AC converter, the situation of expression three-phase modulations.In this performance plot, expression U phase terminal voltage 41, V phase terminal voltage 42, W phase terminal voltage 43.These terminal voltages are to realize by the duty ratio shown in the longitudinal axis (%) in the PWM modulation.
Fig. 3 is the timing diagram of the interior conversion of the carrier cycle of three-phase modulations, upper arm switching element U, V, W in the expression carrier cycle, an example of underarm switch element X, Y, Z conduction and cut-off (ON/OFF).This generally is implemented by the timer function of triangular wave and microcomputer.But,, omitted the idle time that is used to prevent short circuit of upper arm switching element and underarm switch element in order to simplify demonstration.The situation of Fig. 3 is near the timing diagram the τ point among Fig. 2.As shown in Figure 3, the conversion of each switch element exists during 4 patterns of (a) and (b), (c), (d), the circuit diagram of the current path explanation during Fig. 4 to Fig. 7 represents during each.
Fig. 4 represent during in (a), upper arm switching element U, V, W all end, underarm switch element X, the whole conductings of Y, Z.U phase current, V phase current are respectively from flowing to stator coil 28 with underarm switch element X, Y diode connected in parallel 3X, 3Y, and the W phase current flows out to underarm switch element Z from stator coil 28.Electric current circulates between underarm and stator coil 28.Therefore, be in the state that the non-energising of power is not provided from 1 pair of DC-to-AC converter 37 of battery.
Fig. 5 represent during in (b), upper arm switching element U conducting, underarm switch element Y, Z conducting.The U phase current flows to stator coil 28 from upper arm switching element U, and the V phase current is from flowing to stator coil 28 with underarm switch element Y diode connected in parallel 3Y, and the W phase current flows out to underarm switch element Z from stator coil 28.Therefore, be in the "on" position that power is provided from 1 pair of DC-to-AC converter 37 of battery.At this moment, flow through the phase current of U phase in the power line.
Fig. 6 represent during in (c), upper arm switching element U, V conducting, underarm switch element Z conducting.U phase current, V phase current flow to stator coil 28 from upper arm switching element U, V respectively, and the W phase current flows out to underarm switch element Z from stator coil 28.Therefore, be in the "on" position that power is provided from 1 pair of DC-to-AC converter 37 of battery.And, flow through the phase current of W phase in the power line.
Fig. 7 represent during in (d), upper arm switching element U, V, the whole conductings of W, underarm switch element X, Y, Z all end.U phase current, V phase current flow to stator coil 28 from upper arm switching element U, V respectively, and the W phase current flow into and upper arm switching element W diode connected in parallel 3W from stator coil 28.Electric current circulates between upper arm and stator coil 28.Therefore, be in the state that the non-energising of power is not provided from 1 pair of DC-to-AC converter 37 of battery.
Fig. 8 represents the example of the direct current in the above-mentioned carrier cycle.During (a) and during (d) do not flow, during (b) flow through the phase current iU of U phase, during (c) flow through the phase current iW of W phase.
As mentioned above, under the conducting of upper arm switching element U, V, W, cut-off state, the electric current of power line is having or not of direct current as can be known, and as can be known this direct current ON time and flow through what kind of electric current etc.Do not have the conducting phase time not flow (non-energising) in upper arm switching element, flow through the electric current (energising) of conducting phase when having only one to be conducted, two flow through the electric current (energising) of residue phase when being conducted, and do not flow during the whole conducting of three-phase (non-energising).
Here, when upper arm switching element has two to be conducted, the underarm switch element conducting of residue phase, it is as follows therefore can to change speech.That is, upper arm switching element flows through the electric current of this conducting phase when having only one to be conducted, and the underarm switch element flows through the electric current of this conducting phase when having only one to be conducted.
Among Fig. 8, with " ON time * iW of the ON time of upper arm switching element U * iU+ underarm switch element Z " later half carrying out of preceding half-sum in carrier cycle, and by removing, thereby can obtain direct current mean value under this carrier cycle with it with the time of carrier cycle.
5 pairs of switch elements 2 that constitute inverter circuit 37 of control circuit are controlled, and have therefore grasped the conduction and cut-off situation and the ON time of upper arm switching element, underarm switch element.In addition, also grasped carrier cycle.Therefore, control circuit 5 can easily calculate the long-pending of the current value that detected by current sensor 6 in time of having only a conducting in the upper arm switching element and this time, and has only the long-pending of the current value that detected by current sensor 6 in time of a conducting and this time in the underarm switch element.
Thus, this value was removed with the time of carrier cycle, thereby can easily be obtained direct current mean value.Thereby this compares with carry out the situation that integration averages with resistance and electric capacity, can calculate immediately.In addition, there be not discrete, the influence that variations in temperature is brought of capacitance of resistance value, the electric capacity of resistance.And then, related between the integrated value that needn't obtain resistance and electric capacity in advance and the actual average current.Thereby obtaining can be with the DC-to-AC converter of the mean value of high precision computation direct current.In addition, do not need resistance and electric capacity integrating circuit, be used for A/D port to the microcomputer in control circuit input average current, therefore can realize miniaturization and improve reliability.
In addition, as shown in Figure 3, as mentioned above, have only the time of a conducting can be replaced into the time of having only two conductings in the underarm switch element in the upper arm switching element, have only the time of a conducting can be replaced into the time of having only two conductings in the upper arm switching element in the underarm switch element.
(execution mode 2)
Fig. 9 represents the circuit diagram of the DC-to-AC converter of embodiments of the present invention 2.Be that with the difference as Figure 24 of the circuit diagram of in the past DC-to-AC converter control circuit 104 becomes control circuit 4, DC-to-AC converter 120 becomes DC-to-AC converter 20, and other are identical and use same label.
The control circuit 4 of DC-to-AC converter 20 is from the phase current values of current sensor 8 input U phases, from the phase current values of current sensor 9 input W phases.In addition, by using the current law of kirchhoff, thereby calculate the phase current values of remaining V phase according to these two current values at the neutral point of stator coil 28.Based on these current values, computing constitutes the induced voltage of 32 pairs of stator coils 28 of Magnmet rotor of motor 31, and the position of Magnmet rotor 32 is detected.Then,, the switch element 2 that constitutes inverter circuit 37 is controlled, by will changing with the PWM modulation, thereby alternating current is outputed to stator coil 28 from the direct voltage of battery 1 based on rotary speed instruction signal (not shown) etc.
Then, control circuit 4 calculates the direct current mean value between battery 1 and the DC-to-AC converter 20 based on above-mentioned resulting U phase, V phase, the W phase current values etc. of each phase mutually.Below be that example illustrates this mean value calculation with the sine wave drive DC-to-AC converter of the alternating current of sine wave output shape.
The relation of the conducting of upper arm switching element U, V, W, cut-off state and direct current is identical with Fig. 2~Fig. 8 in the execution mode 1.Therefore, in Fig. 8, will " in the ON time of upper arm switching element U * this time by in ON time * this time of the detected iU+ underarm switch element Z of current sensor 8 by the detected iW of current sensor 9 " later half carrying out of preceding half-sum in carrier cycle, and by removing, thereby can obtain direct current mean value under this carrier cycle with it with the time of carrier cycle.
Therefore, similarly obtain can be with the DC-to-AC converter of the mean value of high precision computation direct current with execution mode 1.In addition, do not need current sensor 6, operational amplifier 11, resistance and electric capacity integrating circuit, be used for A/D port to the microcomputer in control circuit input average current, therefore can realize miniaturization and improve reliability.
In addition, as shown in Figure 3, have only the time of a conducting can be replaced into the time of having only two conductings in the underarm switch element in the upper arm switching element, have only the time of a conducting can be replaced into the time of having only two conductings in the upper arm switching element in the underarm switch element.
(execution mode 3)
Figure 10 represents the circuit diagram of the DC-to-AC converter of embodiments of the present invention 3.Be that with the difference as Figure 25 of the circuit diagram of in the past DC-to-AC converter control circuit 107 becomes control circuit 7, DC-to-AC converter 122 becomes DC-to-AC converter 22, and other are identical and use same label.
The control circuit 7 of DC-to-AC converter 22 with the shunt resistance of underarm as current detector, according to the phase current of each phase being carried out computing from the voltage of each shunt resistance.Based on this phase current that calculates, rotary speed instruction signal (not shown) etc., the switch element 2 that constitutes inverter circuit 37 is controlled, change by modulating with PWM, thereby alternating current will be outputed to stator coil 28 from the direct voltage of battery 1.
Above action is with identical in the past, but in the present invention, control circuit 7 calculates the direct current mean value between battery 1 and the DC-to-AC converter 22 based on the phase current values of above-mentioned conversion and institute's computing.To this, below be that example describes with above-mentioned sine wave drive DC-to-AC converter.The relation of the conducting of upper arm switching element U, V, W, cut-off state and direct current is identical with Fig. 2~Fig. 8 in the execution mode 1.Therefore, in Fig. 8, with " ON time * iW of the ON time of upper arm switching element U * iU+ underarm switch element Z " later half carrying out of preceding half-sum in carrier cycle, and by removing, thereby can obtain direct current mean value under this carrier cycle with it with the time of carrier cycle.
Figure 11 represents to flow through the electric current of underarm corresponding among Fig. 8.During (a), all the underarm of phases all flows through electric current.That is, flow through the phase current iU of U phase in the underarm of U phase, flow through the phase current iV of V phase in the underarm of V phase, flow through the phase current iW of W phase in the underarm of W phase.And the summation of these electric currents is zero.Here, will be shown in positive number side (upside), its reciprocal ammeter will be shown in negative side (downside) towards the ammeter of battery 1.
During (b), have only the two phase flow overcurrent in the underarm.That is, flow through the phase current iV of V phase in the underarm of V phase, flow through the phase current iW of W phase in the underarm of W phase.These electric currents with equate with U phase current iU mutually.During (c), have only the one phase flow overcurrent in the underarm.That is, flow through the phase current iW of W phase in the underarm of W phase.During (d), do not flow through electric current in the underarm of any phase.
As mentioned above, when having only a conducting in the underarm switch element, it is direct current that the electric current that flows through in the underarm of this conducting phase becomes the electric current that flows through between battery 1 and the inverter circuit 37, in addition, when having only two conductings in the underarm switch element, the electric current that flows through in the underarm of this two-phase and to become the electric current that flows through between battery 1 and the inverter circuit 37 be direct current.
Therefore, will " both conductings simultaneously of the underarm switch element Z of the underarm switch element Y of V phase and W phase time * the W phase that flows through in phase current iV and the W underarm mutually of the V phase that flows through in the underarm of V phase in this time phase current iW's and (=iU)+the phase current iW of the W phase that flows through in the underarm of the interior W phase of ON time * this time of the underarm switch element Z of W phase " later half the carrying out of preceding half-sum in carrier cycle, and by removing, thereby can obtain direct current mean value under this carrier cycle with it with the time of carrier cycle.
Therefore, similarly obtain can be with the DC-to-AC converter of the mean value of high precision computation direct current with execution mode 1.In addition, do not need current sensor 6, operational amplifier 11, resistance and electric capacity integrating circuit, be used for A/D port to the microcomputer in control circuit input average current, therefore can realize miniaturization and improve reliability.
In addition, as shown in Figure 3, have only the time of a conducting can be replaced into the time of having only two conductings in the upper arm switching element in the underarm switch element, have only the time of two conductings can be replaced into the time of having only a conducting in the upper arm switching element in the underarm switch element.
(execution mode 4)
Figure 12 represents the details of the direct current waveform in the carrier cycle.At time tB direct current is iB, is iT at time tT direct current.In Fig. 8, Figure 11, simply current peak is expressed as fixingly, but details tilts as shown in figure 12.
This is from following reason.That is, establish from the applied voltage of 20,21,22 pairs of stator coils 28 of DC-to-AC converter be E, the electric current that flows through is i, time to be that the inductance of t, stator coil 28 is L, then according to the law of electromagnetic induction, E=Ldi/dt sets up.Applied voltage E is a direct current and fixing, so the time rate of change di/dt of current i fixes.That is current i t straight line variation in time.
Therefore, detecting current value at the middle timing t C of conduction period of switch element becomes the median iC that detects electric current, can improve the precision of mean value calculation.
(execution mode 5)
Figure 13 represents the circuit diagram of the DC-to-AC converter of embodiments of the present invention 5.Be that with the difference of Figure 10 in the execution mode 3 control circuit 7 becomes control circuit 10, and DC-to-AC converter 22 becomes DC-to-AC converter 23, other are identical and use same label.Control circuit 7 and control circuit 10 be not both the different of action shown below.
In execution mode 3, such as " both conductings simultaneously of the underarm switch element Z of the underarm switch element Y of V phase and W phase time * the W phase that flows through in phase current iV and the W underarm mutually of the V phase that flows through in the underarm of V phase in this time phase current iW's and (=iU)+the phase current iW of the W phase that flows through in the underarm of the interior W phase of ON time * this time of the underarm switch element Z of W phase " record, the detection of phase current has only one or have only in this time of two conductings and carry out at the underarm switch element.
With respect to this, in the embodiments of the present invention 5, during the whole conductings of underarm switch element, electric current is detected by current detector.During being equivalent among Figure 11 (a).Thus, the precision of direct current mean value will descend to some extent, but 3 can detect mutually simultaneously, and the timing that does not need to detect narrows down to this time, so that current detecting becomes is easy.
Therefore, during the whole conductings of underarm switch element, the phase current iV of V phase, the phase current iW of W phase are detected, and will " both conductings simultaneously of the underarm switch element Z of the underarm switch element Y of V phase and W phase time * the V phase phase current iV and W phase current iW mutually with (=iU)+the phase current iW of ON time * W phase of the underarm switch element Z of W phase " later half the carrying out of preceding half-sum in carrier cycle, and by removing, thereby can obtain direct current mean value under this carrier cycle with it with the time of carrier cycle.
In addition, as shown in Figure 3, have only the time of a conducting can be replaced into the time of having only two conductings in the upper arm switching element in the underarm switch element, have only the time of two conductings can be replaced into the time of having only a conducting in the upper arm switching element in the underarm switch element.
(execution mode 6)
Figure 14 with carrier cycle related in the flow process of mean value calculation of expression direct current.In chronological order carrier cycle is made as carrier cycle A, carrier cycle B, carrier cycle C, transition period shown in Figure 3 is set as follows, carrier cycle A is a0, b0, c0, d0, c0, b0, a0, carrier cycle B is a1, b1, c1, d1, c1, b1, a1, and carrier cycle C is a2, b2, c2, d2, c2, b2, a2.
In the underarm of all phases of carrier cycle A, flow through electric current during (a0), the underarm electric current is detected.According to the conversion (b0) of this electric current and the carrier cycle A that determined, the time of (c0), calculate average current.In addition, in order to determine the conversion of next carrier cycle B based on this electric current, beginning PWM modulation operation and in carrier cycle A, finishing.In carrier cycle B, carrier cycle C too.
Figure 15 flow process of the mean value calculation of the above-mentioned direct current of flowcharting.In step 10, judge conversion during whether be flow through in the underarm of all phases electric current during (a0).If not during (a0) (N), then wait until become during till (a0).When (a0) (Y),, detect the underarm electric current during becoming in step 20.In addition, in step 30, take out the conversion (b0) of carrier cycle A, the time data of (c0).Then, in step 35, according to these electric currents, Time Calculation average current.In step 40, in order to determine the conversion of next carrier cycle B based on above-mentioned electric current, beginning PWM modulation operation and in carrier cycle A, finishing.
(execution mode 7)
Figure 16 represents the flow process of mean value calculation of the direct current of embodiments of the present invention 7.Be with the difference of Figure 14, according to calculating average current the change-over time of previous carrier cycle.
Figure 17 is about the flow process of carrier cycle B with the mean value calculation of the described direct current of flowcharting.In step 50, judge conversion during whether be flow through in the underarm of all phases electric current during (a1).If not during (a1) (N), then wait until become during till (a1).When (a1) (Y),, detect the underarm electric current during becoming in step 60.In addition, in step 70, take out the conversion (b0) of carrier cycle A, the time data of (c0) from preserving the destination.In addition, in step 75,, preserve the conversion (b1) of carrier cycle B, the time data of (c1) for the calculating in carrier cycle C.Then, in step 80, according to these electric currents, Time Calculation average current.In step 90, in order to determine the conversion of next carrier cycle C based on above-mentioned electric current, beginning PWM modulation operation and in carrier cycle B, finishing.
Thus, the timing by the conducting of underarm switch element and detected timing related of current value by current detector can improve the mean value calculation precision of direct current.
(execution mode 8)
Figure 18 represents the flow process of mean value calculation of the direct current of embodiments of the present invention 8.Be with the difference of Figure 16, calculate average current according to the electric current of previous carrier cycle and the electric current of this carrier cycle.As an example, the electric current of previous carrier cycle and the electric current of this carrier cycle are averaged.Thus, by averaging, can improve the mean value calculation precision with changing the electric current that goes down in the carrier cycle.Weighting is also passable in the electric current of the electric current of previous carrier cycle and this carrier cycle.
(execution mode 9)
Figure 19 is illustrated in the underarm electric current from carrier cycle A to carrier cycle B.The phase current iW of the phase current iU of U phase, the phase current iV of V phase, W phase is semi-continuously flowing through to the preceding of carrier cycle B from the later half of carrier cycle A.The mid portion of the electric current that this is continuous does not excessively change and stablizes.
Therefore, detect the current value of underarm by near the γ starting point of β, carrier cycle the B terminal point of carrier cycle A near, promptly, by near the starting point of carrier cycle or near the timing the terminal point detect the current value of underarm, can prevent to improve the precision of mean value calculation because of excessively changing the error of the current detection value that causes.
(execution mode 10)
Figure 20 represents the circuit diagram of the DC-to-AC converter of embodiments of the present invention 10.Deleted the shunt resistance 16 in the DC-to-AC converter 23 (Figure 13) of the DC-to-AC converter 22 (Figure 10) of execution mode 3 or execution mode 5.In the example of execution mode 3, execution mode 5,, just can calculate the mean value of direct current if know that the phase current of two-phase is the value of phase current iU with the W phase current iW mutually of U phase.Therefore, only about the mean value calculation of direct current, as long as two shunt resistances promptly be used for the U phase shunt resistance 15, be used for the shunt resistance 17 of W phase.But current detector has only two, therefore detectable phase place during be defined.
Investigate among Fig. 2 detectable during, then during this period during U phase terminal voltage 41 maximums and W phase terminal voltage 43 minimums, perhaps, during W phase terminal voltage 43 maximums and U phase terminal voltage 41 minimums.Instantaneous power is fixed.Therefore, during this, can calculate the mean value of direct current.
Thereby, can reduce the number of current detector, help the miniaturization of DC-to-AC converter.In addition, Gai Qijian phase width is respectively 60 degree.Therefore, by in the phase width of 60 degree, calculating the mean value of direct current, can improve precision.
In addition, in the above-described embodiment, represented not have the situation of the shunt resistance 16 of V phase, even but the shunt resistance of other phases also is to change during detectable and problem not.In addition, the time α in Fig. 2 does not have to have only in the underarm switch element time of two conductings.And, there is the time of having only a Z conducting in the underarm switch element.Therefore, if only regularly carry out the calculating of the mean value of direct current, as long as then be used for the shunt resistance 17 of W phase at this.
(execution mode 11)
Long-pending for current value and time, can be only preceding half or later half obtaining of carrier cycle, and remove with half time of carrier cycle, thereby replacement is obtained at later half two parts of preceding half-sum of carrier cycle.Thus, the operation times that constitutes the microcomputer of control circuit reduces, and can reduce the heavy burdens.In addition,, then can eliminate current detecting error etc., the precision of mean value is improved if in a plurality of carrier cycles, calculate the mean value of direct current.
(execution mode 12)
The phase current (iW) 53 of the phase current (iV) 52 of the phase current (iU) 51 of expression phase place and U phase, V phase, W phase is related among Figure 21.It is to take turns that the electric current that phase place causes changes with 360 degree phase widths.In addition, as shown in Figure 8, these phase currents occur in direct current.Therefore, in DC-to- AC converter 20,21,22,23,, make the average current that is associated with the caused phase place of commentaries on classics distance change even load change one and take turns, thereby obtain correct mean value by calculate the mean value of direct current at each 360 degree phase width.
Have in the motor of Magnmet rotor in no transducer DC Brushless Motor etc., because the number of poles of Magnmet rotor, and make 360 degree phase widths not necessarily consistent with a commentaries on classics of Magnmet rotor.Therefore, by being to calculate the mean value of direct current during one of motor changes at Magnmet rotor, thereby obtain changeing also having comprised in one of motor changes the correct direct current mean value that waits the electric current change that brings apart from change.
Because therefore three-phase equilibrium in 360 degree phase widths, is equivalent to three times of direct current mean values that just equal to be equivalent to three-phase of the direct current mean value of a phase.Therefore, as long as calculate the direct current mean value that is equivalent to a phase, just can calculate the direct current mean value that is equivalent to three-phase, thereby about the specific phase current in the represented phase current of Fig. 8 (being iU or iW among Fig. 8), as long as in 360 degree phase widths, calculate.Therefore, the direct current mean value calculation becomes easy.
(execution mode 13)
Figure 22 represents DC-to-AC converter of the present invention and compressor one are constituted, and is applied to aircondition and is installed to a example in the vehicle.DC-to-AC converter electric compressor integral 61 and outdoor heat converter 63, outdoor bellows 62 are installed in the enging cabin in the place ahead of vehicle 60.On the other hand, dispose indoor Air Blast fan 65, indoor heat converter 67, air-conditioner controller 64 in the vehicle chamber.Suck the car outer air from air-in 66, and will in car, blow out by the air that indoor heat converter 67 has carried out heat exchange.
Vehicle, particularly in electric automobile and hybrid automobile, consider from guaranteeing aspects such as rideability, taking property, air conditioner for vehicles also requires small-sized light weight, wherein, in weight and narrow motor compartment are arranged and the miniaturization and of the motor compressor of being installed in other the space be important topic.
DC-to-AC converter of the present invention can realize miniaturization by the structure shown in the respective embodiments described above, as long as one is installed to the miniaturization that just can realize compressor self in the compressor.Therefore, to be used in the aircondition that uses in these vehicles or the general aircondition all be fit closely to DC-to-AC converter of the present invention.Especially, can correctly calculate consumed power, therefore can help the energy-saving operation of air-conditioning from DC power supply.
In addition, in the respective embodiments described above, represented the example of motor, but also can be useful in transformer etc. as load.In addition, do not have special motors, any one of induction motor, no transducer DC Brushless Motor, reluctance motor etc. can.The PWM modulation is illustrated three-phase modulations, but the two-phase modulation can be suitable for too.In addition, offset of sinusoidal ripple type of drive is illustrated, but also can be applicable to 120 degree step modes etc.Current detector is not limited to shunt resistance, as long as can detect instantaneous peak current.If the time that direct current flows through between DC power supply and inverter circuit and the ON time of switch element equate, but because of operate time of idle time, switch element, diode etc. different.Therefore, also can proofread and correct according to these factors.